Ignition promotor for diesel fuels



Patented Dec. 30, 1941 IGNITION PROMOTOB FOR DIESEL FUELS Gould 11. Cloud, Elizabeth, and Louis A. Mikeska,

Westiield, N. 1., assignors to Standard Oil Development Company, a corporation of Delaware No Drawing. Application July 21, 1938, Serial No. 220,500

10 Claims. (CL 44-9) This invention has as its chief object the improvement of fuels for use in compression-ignition engines and relates particularly to the use of novel addition agents for improving the ignition qualities of hydrocarbon fuels when they undergo combustion in such engines of the high speed Diesel type.

In consideration of increasing the power and fuel economy in the operation of compressionignition engines, principally when the hydrocarbon fuel contains insuflicient amounts of hydrocarbon compounds recognizable as serving these ends by virtue of their suitable ignition qualities, the additions of various oxygen-, nitrogen-, and sulfur-containing organic compounds have been proposed. Hydrocarbon compounds characterized by aromatic hydrocarbons have poor ignition qualities which give rise to the vibrations manifested by knocking" and result in a loss of power.

A poor ignition quality in a fuel is most frequently exhibited by an excessive ignition lag, in other words, an excessive delay between the beginning of fuel injection into the combustion chamber of an engine and the point at which ignition of the injected fuel sets in.

On the other hand, normal aliphatic hydrocarbons have good ignition qualities. Normal cetane, in particular, which serves as a standard of high ignition quality in Diesel fuel rating by recommendation of the S. A. E. VolunteerGroup for Compression-Ignition Fuel Research, has a very short ignition lag. The ignition lag of a fuel consisting of cetane and alphamethyi-naphthalene is shortened very nearly in proportion to the increase in the percentage of cetane by volume in such a blend, and when small amounts of addition agents improve the performance of a.

fuel in the same respect comparable to the improvement made by an increase of about or more of cetane in a blend with alphamethylnaphthalene, such addition agents have been considered as having commercial significance.

The novel addition agents of this invention are characterized by organic compounds containing a thiocarboxylic acid radical, particularly a dithio-carboxylic acid or thiolic acid radical, and those also containing nitrogen. The solution in liquid hydrocarbon fuels of this type of compounds in small amounts for imparting better ignition qualities to the fuels constitutes a more specific object of this invention. Classes of compounds which characteristically contain thiocarboxylic acid radicals are: acyl uuliivzles, xanthates, xanthogenyl sulfides, thic- I. MONOTHIOCARBOXYLIO ACID, 0a THIOLIC Acm DERIVATIVES, I. 15., AcYL SULFIDES i R-s- R I Hts-Hist I? Rt-s-s-s-c-m 0 II U RC-Sfi-S R s for example: v 0 II Ethyl thioacetste, cmc-s c=m II Discetyldisulfido, v CH;CSS-(L)CH; o o I t t Bismethanemrbothiolsuliide, CH; -SSS --CH;

0 Bismethauecarbothiol disulfide, C H;&- S S S 3 C H:

II. DITHIOCARBOXYLIC Acm DERIVATIVES 4 (a) XanthOgenyl and thioxanthogenul compounds L 5 4o Ro -S R H Ethyl s ethyl mutilate, CzH O Calls ll ll Sulfocaroxylethyl disulfide, 0111.0 C- S S C 0 C H;

nisethylxanthogenyl sulfide. 0111.0 931- S S S g 0 C 1H,

Bisethylthioxanthogenyl sulfide, oinlstis s s e s 0 2H:

(b)- Dithiocarbamates BsN-- S N B1 s mN- 3s mam N=O s for example:

Diethyl ammonium dimethyl n 1 Diamyl-ammonium-diamyl-di- (C;Hu)1N-CSN(ClH.|):

thiocarbamsta. Iii

carbamste.

(c) Thiurams S S RsN-S-NRs S mmLs-samn for example:

"-d-o -cs -c--sare considered essential active parts of the compounds which are suitable for the purposes of the present invention, and preferably the compounds should contain only 2 to 3 sulfur atoms in a straight chain linkage, except when sulfur is Tetmethyl thiuram sulfide,

interlinked between carbon and nitrogen as in the thiocarbamates.

The effectivenes of compounds containing an active thiocarboxylic acid radical in raising the engine performance from crude oils, gas oils,

Fuel tests Percent of Cotsne Compound blended with a 40 octane Columbian gas 011 fifi gf h g3:

Bismethanecarbothiol sulfide 1.0 +5 Bismethanecarbothiol dlsulflde. 1.0 +9 Bisamylthioxanthogenyl sulfide 3. 0 +0 Sulfocarboxylethyl disulilde. 3.0 +8. Bisethylxanthogenyl sulfide 3. 0 +15 Dimethyl ammonium climethyl dithiocarbamate 3. 0 +5 Diethyl ammonium diethyl dithiocarhamate 1.0 +10 'Istramethyl thiuram disulflde 1.0 +0 Sodium N-dibutyl dithiocarbsmsto. ...l. 3. 0 +6 The proportion of the ignition quality improving agent to be added to the hydrocarbon fuel may range from a fraction of one percent to the limit of solubility in the fuel, but preferably from about .025 to 5%. A gas oil boiling from about 400 F. to 700 F., or 750 F., or, in general, having asuitable. boiling range for use as a fuel in Diesel type engines may be used as the hydrocarbon fuel. Under some circumstances, an more narrowly cut fraction such as one distilling from about 400 F. to 600 Fzor from 500' 1". to 700' I". may be used. Ordinarily, the hydrocarbon fuel may be said to have a boiling range above that of gasoline.

This invention makes commercially feasible the preparation of Diesel fuels giving satisfactory residual fuels having low pom points, low A. P. I. gravities, and high heat values, such as those procured from naphthene base, asphalt base, or

- mixed base stocks by the addition of'active compounds, described, in small quantities. The burning qualities of gas oils from para-mu crudes are also enhanced by these novel addition agents.

Small quantities of the novel addition agen of this invention may be used for adapting various mixtures of hydrocarbons for use as Diesel fuels, including recycle stock from a operation, non-paraflinic extracts, oils from destructive distillations of pyrobitmninous and asphaltic materials, mixtures of these with one another or with crude petroleum fractions. other agents for enhancing various other qualities without detracting' substantially from the ignition qualities of the fuel may be admired. such as, voiliness agents, sludge dispersers, dyes, corrosion inhibitors, anti-oxidants, viscosity improvers, pour depressants, and gum solvents. Also, other promoters of ignition qualities may be admixed.

It is not intended that this invention be limited to the specific examples which are given merely for the sake of illustration. It is daired to claim all the novelty inherent in the invention in the appended claims as broadly as the prior art permits.

We claim: I

1. A fuel for compression-ignition engines of the Diesel type, comprising essentially a hydrocarbon fuel and a small amount of about 1% to about 5% of an organic compoimd containing a thiocarboxylic acid radical for imparting better ignition qualities to the fuel.

2. A fuel for compressimi-ignition engines of the Diesel type, comprisin essentially a hydrocarbon fuel and a small amount of about 1% to about 5% of an acyl sulfide for imparting better ignition qualities to the fuel.

4. A fuel for compression-ignition engines of the Diesel type, comprising essentially a hydrocarbon fuel and a small amount of bisrnethanecarbothiol disulfide for imparting better ignition qualities to the fuel. p

5. A fuel for compression-ignition engines of the Diesel type, comprising essentially a hydrocarbon fuel and a small amount of about 1% to about 5% of an organic compound containing a dithiocarboxylic acid radical for imparting better ignition qualities to the fuel.

6. A fuel for compression-ignition engines of the Diesel type, comprising essentially a hydrocarbon fuel and a small amount of a compound containing a xanthogenyl group imparting better ignition qualities to the fuel. a

7. A fuel for compression-ignition engines of the Diesel type, comprising essentially a hydrocarbon fuel and a small amount of bisethylxanthogenyl sulfide for imparting better ignition qualities to the fuel. v

8. A fuel for compression-ignition engines of the Diesel type, comprising essentially a hydro-.

carbon fuel and asmall amount of an organic compound containing an active thiocarboxylic acid radical with 2 to 3 sulfur atoms in a straight chain linkage to impart better ignition qualities to the fuel.

9. An improved diesel fuel oil containing, in

sufficient amount to raise the.cetane number of the oil, a compound having the formula R-Y- SS( 3YR' wherein R. and R are hydrocarbon radicles and Y is sulfur or oxygen.

10. An improved Diesel fuel comprising a hydrocarbon Diesel fuel oil andin admixture therewith 'sulfocarboxylethyl disulfide in an amount sufficient to decrease the ignition delay period of the fuel. v

GOULD H. CLOUD.

LOUIS A. MIKESKA. 

